Remote control circuit and apparatus for exploding explosives

ABSTRACT

A remote control circuit and apparatus for exploding explosives. Electric power generated at a resonance circuit when it is tuned to a control electromagnetic field is used to charge an ignition condenser. Provision is made for a control circuit including a controlled rectifier called a triac. The control circuit is adapted to generate a starting pulse at an instant when the control electromagnetic field is extinguished. The starting pulse serves to make the controlled rectifier conductive and hence discharge the ignition condenser through a detonator, thereby initiating it and exploding blasting explosives used to break rock and other solid material.

Unite Ueda et a1.

States Patent [191 Sept. 10, 1974 [30] Foreign Application Priority Data June 23, 1972 Japan 47-62981 [52] US. Cl. 102/22, 102/702 R, 317/80 [51] Int. Cl F42b 3/00, F42d 3/00, F42c 13/00 [58] Field of Search 102/70.2 R, 22; 317/80 [56] References Cited UNITED STATES PATENTS 5/1930 Bleecker 102/702 R 2/1965 Hinman, Jr. 102/702 R 3,780,654 12/1973 Shimizu et a1. 102/702 R Primary ExaminerBenjamin A. Borchelt Assistant Examiner-C. T. Jordan Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57] ABSTRACT A remote control circuit and apparatus for exploding explosives. Electric power generated at a resonance circuit when it is tuned to a control electromagnetic field is used to charge an ignition condenser. Provision is made for a control circuit including a controlled rectifier called a triac. The control circuit is adapted to generate a starting pulse at an instant when the control electromagnetic field is extinguished. The starting pulse serves to make the controlled rectifier conductive and hence discharge the ignition condenser through a detonator, thereby initiating it and exploding blasting explosives used to break rock and other solid material.

2 Claims, 7 Drawing Figures PAIENIED SEP 1 0 I874 SHEET 2 BF 2 REMOTE CONTROL CIRCUIT AND APPARATUS FOR EXPLODING EXPLOSIVES This invention relates to a remote control circuit and apparatus for exploding explosives used to break rock and other solid material.

All of the apparatuses for exploding explosives which have heretofore been used in general consist of a wired apparatus comprising an ignition circuit and an electric detonator, both being interconnected through electric wires.

However, such wired apparatus has the disadvantage that it is difficult to connect the ignition circuit to the electric detonator by means of the electric wires under such conditions as in the sea where violent tidal current is present, etc., and as a result, it has been required to explode the explosive in a remotely controlled manner.

For this purpose, it has heretofore been proposed to provide a remote control apparatus for exploding explosives with the aid of signals such as supersonic waves, shock waves under water and light rays, etc. All of these remote control apparatuses, however, have the disadvantage that provision must be made for an electric detonator and a battery for supplying a current thereto, both being connected in the same circuit.

Such disdvantage will now be described with reference to FIG. 1 showing a representative remote control apparatus for exploding explosives by means of supersonic waves. The remote control apparatus shown in FIG. 1 comprises a control device for radiating supersonic waves and areceiving device consisting of an ignition circuit having an electric detonator 1, a relay 2 and a battery 3 for supplying a current to the electric detonator 1 and a control circuit 4 for receiving the supersonic waves 5 and coupled to the relay 2 of the ignition circuit. The control device arranged distant from the receiving device serves to radiate the supersonic wave-s 5 which upon being received by the control circuit 4 causes it to open or close the relay 2. Ifthe relay 2 is closed, a current flows from the battery 3 through the electric detonator 1 to ignite it and to explode the blasting explosive, thereby completing the blasting operation. Even though provision is made of a safety device for preventing erroneous operation, the presence of the battery 3 could cause an accidental supply of current from the battery 3 to the electric detonator 1, thereby causing an accidental explosion of the explosives. Thus, the apparatus shown in FIG. 1 is not safe in handling and installing thereof. In addition, the above mentioned receiving device including the ignition circuit is complex in construction and hence considerably expensive, and as a result, such receiving device is not suitable as one which is completely exhausted after one shot of the explosive has been effected. Moreover, the battery used as the power source is always in the ignition circuit during a period of time from its installation to the explosion of the explosive and hence becomes considerably consumed so that it is impossible to reliably explode the explosive in a stable manner, and that the use of a battery results in a limitation in time.

An object of the invention is to provide a remote control circuit and apparatus for exploding explosives without using a battery, etc. as a power source, which can charge a condenser by means of an electromagnetic field before the ignition of the explosive and which is extremely simple in construction, reliable and safe in operation and can be manufactured in a less expensive manner. I

The invention will now be described in greater detail with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic circuit diagram of a remote control apparatus for exploding explosives;

FIG. 2 is a schematic circuit diagram- 0f a remote control circuit and apparatus for exploding explosives according to the invention;

FIG. 3 is a simplified schematic circuit diagram of the remote control circuit shown in FIG. 2; and

FIGS. 4A to 4D are pulse shape diagrams illustrating a manner by which the remote control circuit and apparatus for exploding explosives according to the invention shown in FIG. 2 may be operated.

In FIG. 2 and FIG. 3 is shown one embodiment of the invention in which reference numeral 6 designates a loop antenna for radiating an electromagnetic field to a control circuit 8. A control oscillator 7 is connected with the loop antenna 6. From the oscillator 7 an alternating current power having a frequency of several KHz is supplied to the loop antenna 6 which then radiates the strong electromagnetic field. The control circuit. 8 ishermetically sealed in a plastic container and comprises a resonance circuit consistingof' an antenna coil 9 and a condenser 10 connected in: parallel with each other. The resonance circuit comprising, the an tenna coil 9 andcondenser 10 are adapted to be tuned to the electromagnetic field radiated from the loop antenna 6 so as to induce an alternating current voltage in the antenna coil 9. Across the condenser 10 are'connected a diode 11 and a large capacity ignition condenser 1-2 connected in series with each other. An ignition switch circuit Ig and a heating bridge 21 of anelectric detonator 19 are connected in series across the large capacity ignition condenser 12'. Across the condenser 10 is also connected a series circuit including a switch starting circuit St, the ignition switch circuit Ig and the heating bridge 21 of the electric detonator 19.

The switch starting circuit St may preferably be composed of a diode 13, a small capacity condenser 14, a field effect transistor 15 and a resistor 18. The ignition switch circuit lg may preferably be composed of a controlled rectifier 16 called a triac.

As shown in FIG. 2, the diodes 11 and I3 are connected in opposite polarity, that is the diode 11 becomes conductive when a positive potential is applied to its anode from the resonance circuit 9, 1 0 and the diode 13 becomes conductive when a negative potential is applied to its cathode from the resonance circuit 9, 10. The small capacity condenser 14 and the resistor 18 of the switch start circuit St are connected in parallel and this parallel circuit is connected between the common connection point between the anode of the diode 13 and the gate electrode of the field effect transistor 15 on the one hand, and the cathode of the controlled rectifier 16 on the other hand.

The gate electrode 17 of the controlled rectifier 16 is connected with the drain of the field effect transistor 15. The source electrode of the field effect transistor 15 is connected to a common connection point between the cathode of the diode 11 and the anode-of the controlled rectifier l6.

The operation of the remote control circuit and apparatus shown in FIGS. 2 and 3 is as follows.

The alternating current power having a frequency of several KI-Iz is supplied from the oscillator 7 to the loop antenna 6 which generates a strong electromagnetic field. The resonance circuit consisting of the antenna coil 9 and the condenser 10 is tuned to the frequency of the electromagnetic field to induce an alternating current voltage shown in FIG. 4A in the antenna coil 9. This alternating current voltage is supplied through the diode 1 l to the large capacity ignition condenser 12 so as to positively charge it as shown in FIG. 48. At the same time, the alternating current voltage generated at the antenna coil 9 and of which the pulse shape is shown in FIG. 4A is supplied through the diode 13 to the small capacity condenser 14 so as to negatively charge it in a rapid manner. Thus, the gate of the field effect transistor 15 is kept at a negative potential, and as a result, no current flows through the field effect transistor 15. Thus, the potential of the gate 17 of the controlled rectifier 16 becomes zero so that no current flows through the controlled rectifier 16.

When the oscillator 7 is made inoperative at an instant when the large capacity condenser 12 has been sufficiently charged as shown in FIG. 4B, the small capacity condenser 14 is suddenly discharged through the resistor 18 to decrease the negative gate potential of the field effect transistor 15, thereby making it conductive. As a result, a starting voltage as shown in FIG. 4C is applied from the drain electrode of the field effect transistor 15 to the gate 17 of the controlled rectifier 16 which then becomes conductive to connect the large capacity ignition condenser 12 across the heating bridge 21 of the detonator 19. Thus, the large capacity ignition condenser 12 is discharged through the heating coil 21 to supply a discharge current as shown in FIG. 4D to the heating bridge 21 to cause explosion of the detonator 19 and hence explode blasting explosive 20 for breaking rock and other solid material 22.

As explained hereinbefore, the use of the measures describe ensures explosion in a safe manner and provides a number of advantages. In the first place, very weak electric power is used for a sufficiently long time to charge the large capacity ignition condenser 12 contrary to the case in which the detonator is directly ignited with the aid of radio waves. Secondly, the control circuit is not required to incorporate batteries therein and by making the oscillator 7 inoperative it may be ensured that the detonator 19 can instantaneously be ignited in a stable and safe manner. Third, a number of control circuits arranged in the electromagnetic field emitted from the sending antenna 6 may simultaneously be ignited to explode a corresponding number of explosives at the same time and hence the invention provides significant utility in the explosive blasting industry. Fourth, the remote control circuit and apparatus according to the invention is not provided with a power source such as batteries so that when preparing the explosive blasting operation there is no danger of the explosive being exploded by accidental shots thereof, and a result, a number of operatives for installing the ingition circuits can be effected in a safe manner. Finally, the remote control circuit and apparatus according to the invention do not deteriorate with the lapse of time so that it is possible to instantly and reli ably operate the ignition circuit after it has been left inoperative for a long time.

The invention makes use of the electromagnetic field whose frequency is several KHz which is not used in common radio communications and electric supply sources. As a result, at places where the remote control circuit and apparatus according to the invention are arranged, there is no strong electric fields which are sufficient to operate the control circuit thereof. In addition, the electromagnetic field is received by the tuned antenna coil so that there is no risk of the ingition circuit being erroneously operated by the presence of electromagnetic waves whose frequencies are different from several KHz.

The control circuit of the remote control circuit and apparatus according to the invention may be embedded in the ground and may be remotely controlled from the loop antenna 6 of the control device arranged distant therefrom.

What is claimed is:

1. A remote control circuit for exploding explosives comprising a control circuit comprising a. a circuit including a resonance circuit adapted to be tuned to a control electromagnetic field and an ignition condenser adapted to be charged by an electric power generated at said resonance circuit when tuned to said control electromagnetic field, and

b. an ignition circuit including a controlled rectifier for generating a starting pulse at an instant when said control electromagnetic field is extinguished and discharging the electric power of said ignition condenser through a detonator.

2. A remote control apparatus for exploding explosives comprising a control circuit comprising a. a circuit including a resonance circuit adapted to be tuned to a control electromagnetic field and an ignition condenser adapted to be charged by electric power generated at said resonance circuit when tuned to said control electromagnetic field, and

b. an ignition circuit including a controlled rectifier for generating a starting pulse at an instant when said control electromagnetic field is extinguished and discharging the electric power of said ignition condenser through a detonator, and

c. a control device including an oscillator and a loop antenna and adapted to remotely control said circuit for exploding explosives. 

1. A remote control circuit for exploding explosives comprising a control circuit comprising a. a circuit including a resonance circuit adapted to be tuned to a control electromagnetic field and an ignition condenser adapted to be charged by an electric power generated at said resonance circuit when tuned to said control electromagnetic field, and b. an ignition circuit including a controlled rectifier for generating a starting pulse at an instant when said control electromagnetic field is extinguished and discharging the electric power of said ignition condenser through a detonator.
 2. A remote control apparatus for exploding explosives comprising a control circuit comprising a. a circuit including a resonance circuit adapted to be tuned to a control electromagnetic field and an ignition condenser adapted to be charged by electric power generated at said resonance circuit when tuned to said control electromagnetic field, and b. an ignition circuit including a controlled rectifier for generating a starting pulse at an instant when said control electromagnetic field is extinguished and discharging the electric power of said ignition condenser through a detonator, and c. a control device including an oscillator and a loop antenna and adapted to remotely control said circuit for exploding explosives. 